Zhao Linfeng

Research on coordinated control of electronic stability program and active suspension system based on function allocation and multi-objective fuzzy decision

The stabilities of the handling and rollover are the two important performance of the vehicle and play an important role in vehicle safe driving. Focusing on improving the handling and rollover stabilities, a new approach to realize the coordinated control of the electronic stability program and the active suspension system is proposed. The vehicle model including the active suspension system has been built. The distance between vehicle centroid and the front and rear axles is estimated by the forgetting factor recursion least squares method on the basis of the vertical motion of the vehicle. The parameter self-tuning fuzzy proportional–integral–derivative control of the electronic stability program is adopted and the 2-degree-of-freedom vehicle model considering the changes of the distance between vehicle centroid and the front and rear axles is treated as the reference model. The active suspension system controller is designed according to the different functions of the active suspension system in different vehicle status areas. The function allocation controller is also designed using multi-objective fuzzy decision, which is used to realize the allocation control of the active suspension system and electronic stability program. Under the double-lane change conditions, the function allocation control has been simulated based on MATLAB/Simulink software, which results indicate that the function allocation control strategy of electronic stability program and active suspension system can significantly improve the manipulation and rollover stability of the vehicle at a high speed under emergency steering. Finally, the function allocation controller is installed to the active suspension system and electronic stability program hardware-in-loop test platform, and the hardware-in-loop test has been done, which results are consistent with the results of simulation.

Vehicle lateral motion chaos analysis based on the Lyapunov exponent method and sliding mode variable structure control

In this paper, a 3-DOF nonlinear model including the yaw, lateral and rolls motion was constructed, and then the chaos numerical simulation analysis was performed based on the Lyapunov exponent method. Through the Lyapunov exponent and bifurcation diagrams, the vehicle motion was relatively complex, containing double-periodic, quasi-periodic and chaotic motions, which was harmful for the stability of the lateral motion of vehicles. In order to realize the control of chaos during vehicle lateral motion, the SMVSC controller was designed by using the sliding mode variable structure control (SMVSC) method. To decrease the chattering of the SMVSC system and further improve the stability of vehicle lateral motion under extreme operation conditions, the adaptive power reaching law was realized by using the fuzzy control method. Finally, the SMVSC system based on the designed adaptive reaching law was simulated in the Matlab/simulink, and the simulation results of uncontrol, SMVSC control and SMVSC control based on the adaptive reaching law were compared. It can be found that the SMVSC control based on the adaptive reaching law can present better performance than that of others by effectively suppressing the chaos during vehicle lateral motion and significantly improving the stability of vehicle lateral motions under extreme operation conditions. Therefore, it is proved that the control strategy is effective.